In wireless communication networks, a UE (user equipment) which needs to transmit data typically first needs to setup a connection to the wireless communication network. In the LTE (Long Term Evolution) technology specified by 3GPP (3rd Generation Partnership Project) the connection setup involves performing an RRC connection establishment procedure between the UE and an eNB. The RRC connection establishment procedure is for example described in 3GPP TS 36.331 V14.4.0 (2017 Sep.), section 5.3.3. Further, the connection setup involves that the eNB forwards an Initial UE Message by NAS (Non Access Stratum) transport to an MME (Mobility Management Entity). The Initial UE Message procedure is for example described in 3GPP TS 36.413 V14.4.0 (2017 Sep.), section 8.6.2. Further, the connection setup involves a context setup procedure and a bearer setup procedure between the eNB and the MME. The context setup procedure is for example described in 3GPP TS 36.413 V14.4.0 (2017 Sep.), section 8.3.1, and the bearer setup procedure is for example described in 3GPP TS 36.413 V14.4.0, section 8.2.1. Further, the connection setup involves establishment of a tunnel management session between the MME and an SGW (Serving Gateway), as for example described in 3GPP 29.274 V14.5.0 (2017 Sep.), sections 7.2.1 and 7.2.2.
In the above connection setup, the RRC Connection Request message from the UE to the eNB typically indicates an establishment cause, such as MO (mobile originating) data, MO signalling, MO voice call, MT (mobile terminating) access as well as an UE identity, e.g., in terms of an S-TMSI (SAE Temporary Mobile Station Identifier). The UE identity is used for identification of the UE in the connection setup procedures.
However, in some cases in may occur that the UE sends two RRC Connection Request messages, each indicating a different establishment cause, in quick succession. Specifically, the UE may send a first RRC Connection Request message, resulting in successful RRC connection establishment, and then send a second RRC Connection Request message. This may for example result from different upper layer processes in the UE independently triggering the connection setup. In the above-mentioned connection setup procedures this has the effect that the MME identifies two Initial UE Messages with different establishment causes from the same UE and releases the already established RRC connection and the related context of the UE. This behavior is based on the MME being implemented in such a way that in abnormal conditions a new context for the connection is established at the cost of an already existing one. While this prioritization of the newly established context over the existing one may help to resolve conflicts and ensure consistent behavior, it may also adversely affect operation of the UE, e.g., by causing a delay or dropping of a call being established.
Accordingly, there is a need for techniques which allow for efficiently and reliably controlling connection setup in a wireless communication network.